Flutter suppression of an aircraft wing with a flexibly mounted mass using magneto-rheological damper

2019 ◽  
Vol 234 (3) ◽  
pp. 827-839
Author(s):  
Amir Hossein Ghasemikaram ◽  
Abbas Mazidi ◽  
Mohammad Reza Fazel ◽  
Seyed Ahmad Fazelzadeh
Keyword(s):  
Differential Equations ◽  
State Feedback ◽  
Structural Model ◽  
Aerodynamic Force ◽  
Governing Equations ◽  
Aircraft Wing ◽  
Flutter Suppression ◽  
Flutter Analysis ◽  
Finite State ◽  
Magneto Rheological

Flutter analysis and suppression of an aircraft wing with a flexibly mounted external store using a magneto-rheological damper are investigated. The wing performs as a cantilever beam and the structural model, which incorporates bending-torsion flexibility, is used. A modified Bouc–Wen model is utilized in order to model the elastic connection between the store and the wing. The modified Peter’s finite-state loading is also considered to simulate the aerodynamic force and moment. The governing equations are obtained via Hamilton’s principle and assumed modes method is subsequently applied to transform the resulting partial differential equations into a set of ordinary differential equations. Numerical simulations are validated against several previously published papers by using a clean Goland wing. In order to control the vertical and rotational vibrations of the store and the wing, a state feedback controller and a compensator with full-order observer are designed. The performance of these controllers is compared together in several situations. Eventually, the performances are treated when disturbance is applied to the system. The results show that magneto-rheological damper’s performance is suitable for controlling the limit cycle oscillations of the wing and external store, in flutter condition.

Analytical and Experimental Flutter Analysis of a Typical Wing Section Carrying a Flexibly Mounted Unbalanced Engine

2019 ◽  
Vol 19 (02) ◽  
pp. 1950013 ◽  
Author(s):  
A. S. Mirabbashi ◽  
A. Mazidi ◽  
M. M. Jalili
Keyword(s):  
Stability Domain ◽  
Governing Equations ◽  
Lagrange Equations ◽  
Wing Section ◽  
Unbalanced Force ◽  
Engine Thrust ◽  
Finite State Model ◽  
Flutter Analysis ◽  
Finite State ◽  
The Stability

In this paper, both experimental and analytical flutter analyses are conducted for a typical 5-degree of freedon (5DOF) wing section carrying a flexibly mounted unbalanced engine. The wing flexibility is simulated by two torsional and longitudinal springs at the wing elastic axis. One flap is attached to the wing section by a torsion spring. Also, the engine is connected to the wing by two elastic joints. Each joint is simulated by a spring and damper unit to bring the model close to reality. Both the torsional and longitudinal motions of the engine are considered in the aeroelastic governing equations derived from the Lagrange equations. Also, Peter’s finite state model is used to simulate the aerodynamic loads on the wing. Effects of various engine parameters such as position, connection stiffness, mass, thrust and unbalanced force on the flutter of the wing are investigated. The results show that the aeroelastic stability region is limited by increasing the engine mass, pylon length, engine thrust and unbalanced force. Furthermore, increasing the damping and stiffness coefficients of the engine connection enlarges the stability domain.

scholarly journals Flutter Analysis of a 3D Box-Wing Aircraft Configuration

2021 ◽  
Author(s):  
Amirhossein Ghasemikaram ◽  
Abbas Mazidi ◽  
S. Ahmad Fazelzadeh ◽  
Dieter Scholz
Keyword(s):  
Aerodynamic Force ◽  
Stability Boundary ◽  
Design Parameters ◽  
Governing Equations ◽  
Geometrical Properties ◽  
Aerodynamic Model ◽  
Flutter Analysis ◽  
Wing Sweep ◽  
Wing Structure ◽  
Good Agreement

The aim of this paper is to present a flutter analysis of a 3D Box-Wing Aircraft (BWA) configuration. The box wing structure is considered as consisting of two wings (front and rear wings) connected with a winglet. Plunge and pitch motions are considered for each wing and the winglet is modeled by a longitudinal spring. In order to exert the effect of the wing-joint interactions (bending and torsion coupling), two ends of the spring are located on the gravity centers of the wings tip sections. Wagner unsteady model is used to simulate the aerodynamic force and moment on the wing. The governing equations are extracted via Hamilton’s variational principle. To transform the resulting partial integro-differential governing equations into a set of ordinary differential equations, the assumed modes method is utilized. In order to confirm the aerodynamic model, the flutter results of a clean wing are compared and validated with the previously published results. Also, for the validation, the 3D box wing aircraft configuration flutter results are compared with MSC NASTRAN software and good agreement is observed. The effects of design parameters such as the winglet tension stiffness, the wing sweep and dihedral angles, and the aircraft altitude on the flutter velocity and frequency are investigated. The results reveal that physical and geometrical properties of the front and rear wings and also the winglet design have a significant influence on BWA aeroelastic stability boundary.

Limit Cycle Flutter Analysis of a High-Aspect-Ratio Wing with an External Store

2014 ◽  
Vol 912-914 ◽  
pp. 907-910 ◽  
Author(s):  
Jun Xu ◽  
Xiao Ping Ma
Keyword(s):  
Aspect Ratio ◽  
Limit Cycle ◽  
High Aspect Ratio ◽  
Structural Model ◽  
Bifurcation Diagrams ◽  
Governing Equations ◽  
Time Simulation ◽  
Flutter Analysis ◽  
Structural Nonlinearities ◽  
Limit Cycle Flutter

Limit cycle flutter analysis of a high-aspect-ratiowing with an external store is presented. The concentrated store mass iscombined into the governing equations which are obtained using the extendedHamilton’s principle. The high-aspect-ratio wing structural model, which alsoconsiders the in-plane bending motion, is used. Three possible nonlinearitiesare considered including structural nonlinearities, aerodynamic nonlinearities,and store nonlinearities. Time simulation and bifurcation diagrams areperformed to analysis systems with three nonlinearities.

Kinematic characteristics of longitudinal double folding wings

2021 ◽  
pp. 1-25
Author(s):  
L. Tiegang ◽  
C. Guoguang ◽  
L. Shuai
Keyword(s):  
Angular Velocity ◽  
Structural Model ◽  
Initial Conditions ◽  
Aerodynamic Force ◽  
Model Simulation ◽  
Lagrange Equation ◽  
Grid Method ◽  
Weapon Systems ◽  
Folding Wing ◽  
Double Folding

ABSTRACT A folding wing is a tactical missile launching device that needs to be miniaturised to facilitate storage, transportation, and launching; save missile and transportation space; and improve the combat capability of weapon systems. This study investigates the aeroelastic characteristics of the secondary longitudinal folding wing during the unfolding process. First, the Lagrange equation is used to establish the structural dynamics model of the folding wing, the kinematics characteristics during the deformation process are analysed, and the unfolding movement of the folding wing is obtained using the dynamic equations in the process. Then, the generalised unsteady aerodynamic force is calculated using the dipole grid method, and the multi-body dynamics equation of the folding wing is obtained. The initial angular velocity required for the deployment of the folding wing is analysed through structural model simulation, and the influence of the initial angular velocity on the opening process is studied. Finally, aeroelastic flutter analysis is performed on the folding wing, and the physical model of the folding wing verified experimentally. Results show that the type of aeroelastic response is sensitive to the initial conditions and the way the folding wing opens.

Robust H2/H∞Control Strategy for Linear Markovian Jump Systems

2014 ◽  
Vol 525 ◽  
pp. 646-652
Author(s):  
Min Bian ◽  
Qing Yun Guo
Keyword(s):  
Control Strategy ◽  
State Feedback ◽  
Control Strategies ◽  
State Feedback Control ◽  
Linear Matrix ◽  
Bounded Real Lemma ◽  
Finite State ◽  
Linear State ◽  
Feasible Solutions ◽  
Jump Systems

The robust H2/<em>H</em>∞ control strategy for a class of linear continuous-time uncertain systems with randomly jumping parameters is investigated. The transition of the jumping parameters is decided by a finite-state Markov process. The uncertainties are supposed to be norm-bounded. It is desired to design a linear state feedback control strategies such that the closed-loop system satisfies H performance and minimizes the H2 norm of the system. A sufficient condition is first established on the existence of the robust H2/<em>H</em>∞controller bases on the bounded real lemma. Then the corresponding state-feedback law is given in terms of a set of linear matrix inequalities (LMIs). It is showed that this condition is equivalent to the feasible solutions problem of LMI. Furthermore, the control strategy design problem is converted into a convex optimization problem subject to LMI constraints, which can be easily solved by standard numerical software.

MULTIBODY DYNAMIC MODELING AND FLUTTER ANALYSIS OF A FLEXIBLE SLENDER VEHICLE

2012 ◽  
Vol 12 (06) ◽  
pp. 1250049 ◽  
Author(s):  
A. RASTI ◽  
S. A. FAZELZADEH
Keyword(s):  
Differential Equations ◽  
Rigid Body ◽  
Dynamic Modeling ◽  
Equations Of Motion ◽  
The Body ◽  
Elastic Deformations ◽  
Strip Theory ◽  
Multibody Dynamic ◽  
Flutter Analysis ◽  
Rigid Body Motions

In this paper, multibody dynamic modeling and flutter analysis of a flexible slender vehicle are investigated. The method is a comprehensive procedure based on the hybrid equations of motion in terms of quasi-coordinates. The equations consist of ordinary differential equations for the rigid body motions of the vehicle and partial differential equations for the elastic deformations of the flexible components of the vehicle. These equations are naturally nonlinear, but to avoid high nonlinearity of equations the elastic displacements are assumed to be small so that the equations of motion can be linearized. For the aeroelastic analysis a perturbation approach is used, by which the problem is divided into a nonlinear flight dynamics problem for quasi-rigid flight vehicle and a linear extended aeroelasticity problem for the elastic deformations and perturbations in the rigid body motions. In this manner, the trim values that are obtained from the first problem are used as an input to the second problem. The body of the vehicle is modeled with a uniform free–free beam and the aeroelastic forces are derived from the strip theory. The effect of some crucial geometric and physical parameters and the acting forces on the flutter speed and frequency of the vehicle are investigated.

scholarly journals Mixed convection of micropolar fluid on a permeable stretching surface of another quiescent fluid

2020 ◽  
Vol 16 (4) ◽  
pp. 487-492
Author(s):  
Nurazleen Abdul Majid ◽  
Nurul Farahain Mohammad ◽  
Abdul Rahman Mohd Kasim ◽  
Sharidan Shafie
Keyword(s):  
Fluid Flow ◽  
Differential Equations ◽  
Mixed Convection ◽  
Micropolar Fluid ◽  
Research Subjects ◽  
Governing Equations ◽  
Stretching Surface ◽  
Shooting Technique ◽  
Micropolar Fluid Flow ◽  
Quiescent Fluid

In recent decades, micropolar fluid has been one of the major interesting research subjects due to the numerous applications such as blood, paint, body fluid, polymers, colloidal fluid and suspension fluid. However, the behavior of micropolar fluid flow over a permeable stretching surface of another quiescent fluid with a heavier density of micropolar fluid under the condition of mixed convection is still unknown. Thus, the current work aims to investigate numerically the mixed convection of micropolar fluid flow over a permeable stretching surface of another quiescent fluid. In this research, the similarity transformation is implemented to reduce the boundary layer governing equations from partial differential equations to a system of nonlinear ordinary differential equations. Then, this model is solved numerically using shooting technique with Runge-Kutta-Gill method and applied in Jupyter Notebook using Python 3 language. The behavior of micropolar fluid in terms of velocity, skin friction, microrotation and temperature are analyzed.

scholarly journals Backstepping-based output regulation of ordinary differential equations cascaded by wave equation with in-domain anti-damping

2018 ◽  
Vol 41 (1) ◽  
pp. 246-262 ◽  
Author(s):  
Jianjun Gu ◽  
Chunqiu Wei ◽  
Junmin Wang
Keyword(s):  
Wave Equation ◽  
Differential Equations ◽  
Ordinary Differential Equations ◽  
State Feedback ◽  
Solvability Condition ◽  
Reference Signal ◽  
Output Regulation ◽  
The Body ◽  
Output Regulation Problem ◽  
Feedback Regulator

Output regulation is considered in this paper for ordinary differential equations cascaded by a wave equation, in which both the body equations and the uncontrolled end are subject to disturbances. The disturbances are generated by an exosystem. A backstepping state-feedback regulator is first designed to force the output to track the reference signal. The design is based on solving cascaded regulator equations, and the solvability condition of the equations is characterized in terms of a transfer function and the eigenvalues of the exosystem. An observer-based output-feedback regulator is then designed to solve the output regulation problem. Finally, the regulator tracking performance is illustrated through numerical simulations.

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